The characterization of the clastic Zubair reservoir is challenging because of the high lamination and the oil properties change making the conventional saturation technique uncertain. A new workflow has been recently established in the newly appraised wells which has involved advanced petrophysical measurements along with the fluid sampling. The new technique has led to identify new HC layers that were overlooked by the previous techniques, thus adding more reserves to the KOC asset.
Because of the high lamination of clastic Zubair formation and the change of the oil properties, the dielectric dispersion measurement was integrated along with the diffusion-based NMR to identify new oil zones that has been initially masked by the resistivity-based approach. The new approach has also provided details on the oil movability and the characterization of its property. As the newly identified layers were identified for the 1st time across the field, the fluid sampling was conducted to confirm the new findings.
The advent of a new logging technology from a multi-frequency dielectric technique deployed over the formation has independently pinned down the HC pays over the Zubair interval, including a new zone below the water column. The zone was initially identified as heavy Tar zone. The advanced diffusion-based NMR was thus conducted and integrated with Dielectrics which has demonstrated the movability of HC using the diffusion-based NMR approach over the newly identified zone. A fluid sampling was later performed which has confirmed the new finding. The new identified zone was initially overlooked by the previous interpretation and extensive modeling over the entire field. The seal mechanism was also explained by taking advantage of the high-resolution dielectric dispersion measurement (mainly the low frequency), which has been also supported by the Images interpretation. This new approach has added an incremental oil storage over the field.
Al-Enezi, Badriya (Kuwait Oil Company) | Liu, Peiwu (Schlumberger) | Liu, Hai (Schlumberger) | Kanneganti, Kousic Theja (Schlumberger) | Aloun, Samir (Kuwait Oil Company) | Al-Harbi, Sultan (Kuwait Oil Company) | Al-Ibrahim, Abdullah (Kuwait Oil Company)
A recent study showed that Tuba reservoir, a limestone-rich formation, has the highest oil in-place of all upcoming reservoirs in North Kuwait. This tight formation has three main layers - Tuba Upper (TU), Tuba Middle (TM), and Tuba Lower (TL) with several reservoir units alternating with non-pay intervals. The reservoir units contain significant proven oil reserves; however, production performance after conventional acid fracturing treatments has been historically subpar. As part of new development plan, two horizontal wells, one in TU and one in TL were drilled to evaluate the production potential of a new completion strategy and technologies.
This paper presents one such technology, a single-phase retarded acid system used as a pilot project study. In contrast with previous conventional emulsified acid systems, the single-phase retarded acid minimized tubing friction, thus enabling high pumping rates for the entire treatment. Alternating with the acid system, a viscoelastic surfactant-based leakoff control fluid system allowed the acid stages to reach deeper into the formation. To aid, degradable fiber technology was pumped in several stages to achieve near-wellbore diversion and further control leakoff into large natural fractures, thus improving the stimulated reservoir volume. These fibers are designed to completely degrade with time and temperature after the treatment. Delivery of the complex acid fracturing treatment was optimized in real time for each stage based on bottomhole pressure trend and response.
Combining a new single-phase retarded acid system with chemical diversion technology has proved to be effective in maximizing lateral coverage and etched fracture half-length. Post-treatment evaluation of TU horizontal well revealed the initial production was as much as 150% higher than offset vertical wells after conventional treatments with gelled acid and as high as 100% higher than a previous multistage horizontal well treated with emulsified acid. The TL horizontal well was just put into production recently and is showing encouraging results considering the lower reservoir quality compared to TU formation.
The success of this technique and technical combination delivered breakthrough results for this region and has engaged new interest in developing the Tuba reservoir.
Almohammad, Humoud (Kuwait Oil Company) | Ayyad, Hazim (Schlumberger) | Sultan, Alaa (Kuwait Oil Company) | Rane, Nitin (Kuwait Oil Company) | Abdulrahim, Khaled (Schlumberger) | Bumajdad, Mohammed (Kuwait Oil Company) | Mehraj, Majid (Schlumberger) | Al-Hamdan, Abdulaziz (Kuwait Oil Company) | Al-Mutairi, Norah (Kuwait Oil Company) | Al-Khamis, Abdulaziz (Kuwait Oil Company) | Al-Derbass, Abdullah (Kuwait Oil Company)
Studying the flow behavior in horizontal section addresses further challenges and complexity. Innovative technologies were developed to overcome the fluid segregation challenges in horizontal sections and cover the entire production profile. In Kuwait, horizontal production logging is typically conveyed on 1.75" electrical coiled tubing which is relatively large size and therefore increases the risk of choking the well or killing low flowrate wells. Also, there is a limitation on the availability of the electrical coiled tubing.
Greater Burgan smart ICD wells require a periodic assessment of the production profile and the contribution from each port to overcome the increasing water cut challenge in such a mature field. To identify the source of water, the engineers planned a new strategy to minimize the choking effect through use of smaller coiled tubing size. However, the available small size coiled tubing are not equipped with an electrical line for real-time data streaming. This challenge was resolved by opting for a horizontal PLT logging recording in a memory mode acquisition.
Running the production logging in memory mode is not unusual in vertical and slightly deviated wells, but it is not common in horizontal wells. Risk assessment was carried out trying to eliminate all the expected obstruction such as having a dummy run while monitoring production behavior on the surface using a testing unit, reducing the coiled tubing speed to avoid disturbing the flow stabilization and watching for any indication of coiled tubing tension-compression changes. A contingency plan was in place, for carrying out a nitrogen activation in case the well chocked below the accurate reading limits during the logging. Following the detailed steps and extensive planned procedure, the logging with memory mode in the horizontal section was successful and resulted in accurate flow profile determination along with contribution from each ICD ports. Using normal coiled tubing instead of the electrical coiled tubing has resulted in reduced operational cost and eliminate the challenge of the limited availability of electrical coiled tubing that was delaying the PLT jobs. The major production logging output was accurately presented from the memory mode.
This paper includes the challenges from using memory production logging in horizontal section. A risk assessment for each of the challenges and contingency plan to apply this method.
Pramudyo, Yuni (ADNOC Onshore) | Al Hosani, Mariam (ADNOC Onshore) | Al Awadhi, Fatima (ADNOC Onshore) | Masoud, Rashad (ADNOC Onshore) | Al Besr, Huda (ADNOC Onshore) | Nachiappan, Ramanathan (ADNOC Onshore) | Al Hosani, Khaled (ADNOC Onshore) | Al Bairaq, Ahmed (ADNOC Onshore) | Al Ameri, Ammar (ADNOC Onshore) | Bertouche, Meriem (Badley Ashton) | Foote, Alexander (Badley Ashton) | Michie, Emma (Badley Geoscience) | Yielding, Graham (Badley Geoscience)
Throughout the UAE and the wider region, several broadly E-W orientated structural lineaments are observed on seismic within the Cretaceous successions and are described as strike-slip faults. However, in the studied field, these features have not been readily observed in well data. Instead, networks of fractures and deformation features are present in core and borehole images. A study was carried out in an attempt to calibrate well and seismic data and to understand the relationship between the seismically-resolved faults and the fractures observed on core. This study focuses on a dataset from the north-east part of the field, which includes BHI images, cores, full 3D CT scans and conventional logs in four penetrations, three of which are horizontal, drilled through the faults; as well as 3D seismic data and relevant derived horizons and fault polygon interpretations.
The available data have been investigated in detail, with all structural features in core, circumferential CT scans and BHI images systematically classified using simple and reproducible descriptive schemes. All the structural features have been orientated using directional data from BHI. The understanding of the character and fill of the fractures observed in core has also been incorporated. A further calibration with seismic and integration of results with information from previous studies allowed a full description of the fracture networks, of their densities within and outside the potential fault corridors of the studied field, as well as an assessment of their potential for reactivation and their possible impact on localised formation compaction.
On the BHI images, several sub-vertical fractures have been identified, consisting mainly of mixed resistivity and resistive fractures, striking dominantly WNW-ESE. Particular zones along the wells have noticeably higher fracture densities, where features are organised in clusters; they are intercalated with zones where fractures are rarer. The clustering of fractures within fracture corridors are believed to be fault-related, subvertical and tabular fracture clusters that traverse an entire reservoir unit vertically and extend for several hundreds to thousands of feet laterally. These zones are believed to represent fracture corridors, which correlate with the structural lineaments observed on seismic.
The fracture corridor network in the study area shows a variable deformation signature at the different scales of observations, but consists mainly of sub-vertical (dominantly >60°) deformation bands (
Centeno, Manuel (Schlumberger) | Krikor, Ara (Schlumberger) | Herrera, Delimar Cristobal (Schlumberger) | Sanderson, Martin (Schlumberger) | Carasco, Anant (Schlumberger) | Dundin, Alexander (Schlumberger) | Salaheldin, Ahmed (Schlumberger) | Jokhi, Ayomarz (Schlumberger) | Ibrahim, Sameh (Schlumberger) | Wehaidah, Talal (Kuwait Oil Company)
The complexity of drilling highly deviated wells in Kuwait drives the need for step changing in the well construction mindset, where severe to complete loss of circulation in Shuaiba formation significantly deteriorate the shale layers in Wara and Burgan formations leading to uncontrolled wellbore stability events. Casing while drilling (CWD) and two-stage cementing with a light density cement slurry were introduced as a technology system to drill the highly deviated complex wells through unstable and highly fractured formations. Fit for purpose engineering processes, advanced software solutions, a tailored bit and a bottom hole assembly dynamically simulated for drilling stability and directional tendency behavior were designed. A special light density cement slurry with high compressive strength was also designed to tackle the lost circulation issues when cementing the casing string. The paper will describe how the technologies can work as one system to solve complicated wellbore problems and address the problematic challenges of drilling unstable shales and fractured formations in the same section of the wellbore. This strategy enabled a significant time saving compared to drilling the section conventionally, removing Non-Productive Time (NPT) resulting from additional trips, cement plugs, stuck pipe, and subsequent sidetracks.
Al-Azmi, Mejbel Saad (Kuwait Oil Company) | Al-Otaibi, Fahad Barrak (Kuwait Oil Company) | Joshi, Girija Kumar (Kuwait Oil Company) | Ameer, Hussain Sulaiman (Kuwait Oil Company) | Ashknani, Esmael Mohammed (Kuwait Oil Company) | Tiwary, Devendra Nath (Kuwait Oil Company) | Saleh, Khaled (Kuwait Oil Company) | Al-Khudari, Abdulaziz Bader (Kuwait Oil Company) | Abdulkarim, Anar (Halliburton) | Lee, Jonathan (Halliburton) | Farhi, Nadir (Halliburton)
Identification and interpretation of fractures, bed boundaries, and borehole breakout from high-resolution images plays a crucial role in optimizing completion design. In low-angle wells drilled with oil-based mud (OBM), images may be acquired using wireline. However, using wireline has been a challenge when inclinations exceed 45°, making logging-while-drilling (LWD) acquisition preferable. This paper presents the first use of a 4¾-in. ultrasonic LWD service to provide high-resolution images to assess fractures in the Marrat formation in North Kuwait.
This paper presents LWD log data and high-resolution acoustic amplitude images used to evaluate carbonates within the Middle and Lower Marrat formations and describes their input into the design of the completion program. The 4¾-in. ultrasonic imaging tool was placed within a complex bottomhole assembly (BHA) composed of density and neutron porosity, acoustic, and nuclear magnetic resonance (NMR) sensors. The methodology used to create high-resolution images for both drilling and wipe run data sets using the logging speed and tool rotation is detailed, along with a description of how the image interpretation was used to optimize the completion design.
The 6-in. borehole sections of the Middle and Lower Marrat formations are known to have prominent open fractures. During drilling, significant mud losses were encountered which required a reduction of mud weight to stabilize the well. From the memory data, 256-sector acoustic amplitude images were interpreted to provide an initial assessment of fractures and geological features. It was observed that an interval of log where mud losses were believed to have occurred corresponded with a large fracture and borehole breakout. In addition, multiple sections of borehole breakout at the top and bottom of the borehole were observed, with bed dip interpretation supporting the known field structure.
Further post-well processing of the acoustic amplitude data was performed which created enhanced-resolution images. The processing method takes all of the raw impedance measurements–up to 2000 acquisitions per second–and re-sectors the data based upon the logging speed and tool rotation. The resulting images (540 sector for the drilled section and 360 sector for the wiped section) enabled identification of 255 features over the logged interval. The interpretation of fractures, their location, and dip and strike directions were used to optimize the completion design.
The ability to acquire high-resolution LWD images in OBM applications within high-angle 6-in. hole sections to identify a wide range of features, including fractures, bed boundaries, and borehole breakout, represents a first in Kuwait. Removing the need to use wireline logging technologies in high-angle wells with wellbore stability concerns helps to reduce well time and logging risk. Deliverables from the 4¾-in. ultrasonic imaging service provide direct input into completion design, helping to optimize production.
AL-Rashidi, Hamad (Kuwait Oil Compaby) | Jamsheer, Abdullah (Kuwait Oil Compaby) | AL-Azmi, Talal (Kuwait Oil Compaby) | Muhsain, Batoul (Kuwait Oil Compaby) | Abu-Eida, Abdullah (Kuwait Oil Compaby) | AL-Methen, Badriya (Kuwait Oil Compaby) | Mousa, Saad (Kuwait Oil Compaby) | AL-Harbi, Faseil (Kuwait Oil Compaby) | Duncan, Bruce (Kuwait Oil Compaby) | Safar, Abdulaziz (Kuwait Oil Compaby) | AL-Azmi, Waled (Kuwait Oil Compaby) | Desoky, Waleed (Kuwait Oil Compaby) | AL-Sabah, Fahad (AL-Thurya) | AL-Yaseen, Musaeb (Burgan One) | AL-Hajri, Mohsen (BG) | AL-Mutwa, Bandar (AAA) | AL-Awadhi, Hisham (AAA) | Almeida, Dwane (BG) | AL-Zanki, Farooq (Burgan One)
The strategy of the Kuwait Oil Company (KOC) is to implement key/emerging technologies at a country wide scale to meet future oil demand and production targets as planned in KPC 2040 strategy through overcome the field's challenges. KOC's Optimization strategy focuses on:
Increased and optimize oil production from production optimizations Extension of field life
Increased and optimize oil production from production optimizations
Extension of field life
Production interruption associated with pressure build up in reservoir, wellbore and flow lines have observed among many wells in West Kuwait fields perforated in Upper Burgan formation, which has a great impact on the company strategy. Tight emulsion phenomena is consider one the most challenging problems in West Kuwait wells due to the nature of asphaltenic crudes and high water cut production percentage. Traditional approaches to reduce high pressure and break the emulsion phase through injecting chemical near wellhead or in annuls is usually not successful in most cases and require large amount of chemical. Due to the complexity of this issue, a novel approach was used in this study to identify the main causes of oil production reduction and overcome the challenge to maximize oil production in West Kuwait fields.
Part of the hydrocarbons generated in the mature kitchens migrate into the conventional traps while the other portions remain in the kitchens as unconventional resources. However, significant part of the generated hydrocarbons could be available in the migration pathways. Hydrocarbons in the migration pathways are either retained in the rocks in migration routes or accumulated in subtle traps due to the presence of heterogeneities along the migration pathways. The migration pathways traps are envisaged to be developed in response to the presence of an equilibrium state between the buoyancy forces that are trying to move the hydrocarbon through the rocks and the capillary pressures in the low permeable layers that are resisting these movements (figure 1). The only requirement to develop such traps is for the capillary pressure to be greater than the migration buoyancy force.
Al-Murayri, Mohammed T. (Kuwait Oil Company) | Kamal, Dawood S. (Kuwait Oil Company) | Khan, Mohammad Y. (Kuwait Oil Company) | Al-Mayyan, Haya E. (Kuwait Oil Company) | Abu Shiekah, Issa (Shell) | Shahin, Gordon T. (Shell) | Shukla, Shunahshep R. (Shell) | Bouwmeester, Ron (Shell) | de Kruijf, Sander (Shell)
An inverted 5-spot Alkaline Surfactant Polymer (ASP) pilot is planned for a giant sandstone reservoir in North Kuwait. Despite the development of a robust lab-optimized ASP formulation at reservoir temperature (90°C) and the execution of a successful Single Well Chemical Tracer Test (SWCTT), the combination of high temperature and divalent ion concentration (∼20,000 ppm) makes the implementation of a successful multi-well ASP pilot very difficult mainly due to the challenge of inorganic carbonate scale. This paper presents some unique challenges in connection with the design of an inverted 5-spot ASP pilot and discusses practical strategies to mitigate them.
Due to the high divalent ion concentration in the formation brine, the design basis for the planned chemical EOR pilot requires pre-flushing the reservoir using softened seawater prior to ASP injection. In the base-case scenario for the pilot, injection and production within the pattern were balanced to target a Voidage Replacement Ratio (VRR) of 1. However, it was realized that such a pre-flush strategy would still present significant carbonate scaling risk at the producers. In view of that, an extended softened-water pre-flush strategy (over-flush) was considered to alleviate the anticipated scaling concerns.
Simulations were carried out to explore various scenarios to work out the optimal over-flush strategy for the pilot to mitigate the potential for scale formation at the producers. It was realized that over-flushing the hot reservoir brine by large volumes of cooler surface water could result in significant cooling of the reservoir prior to ASP injection. This change in reservoir temperature compromises the performance the original lab-optimized formulation that was designed considering a reservoir temperature of 90°C. In view of that, careful re-tuning of the chemical formulation was necessary to make it robust for pilot conditions post softened water over-flushing.
Hussein, Ahmed (Exprogroup) | Alqassab, Mohammed (Exprogroup) | Atef, Hazem (Exprogroup) | Sirdhar, Siddesh (Exprogroup) | Alajmi, Salem Abdullah (KOC) | Aldeyain, Khaled Waleed (KOC) | Hassan, Mohamed Farouk (KOC) | Goel, Harrish Kumar (KOC)
Umm Gudair (UG) field is one of the major oil fields of West Kuwait asset. Wells are tested periodically using multiple conventional test separators and data is subsequently used to update Well Performance "Nodal analysis" and "Live Flow Line Surface Network Model".
A different approach was tested in 2018 for a mature oil field in the Middle East to evaluate the effectiveness of Clamp-On based SONAR Flow Surveillance solution against existing conventional portable test separator. The objective was to check the performance of the SONAR Flow Surveillance on black oil wells at different flowing conditions, and ultimately implement a new approach to increase the testing frequency, reduce any potential of hydrocarbon release, avoid well shutdown, optimize operating costs, and production optimization.
The SONAR Surveillance approach is based on SONAR clamp-on flow meters deployed in conjunction with compositional (PVT) and multiphase flow models for oil and gas wells to interpret the measurements of the SONAR flow meters at line conditions (pressure, temperature, fluid stream composition), and output the gas, oil and water phase flow rates at both actual and standard conditions. The SONAR meter measures the bulk flow velocity (at line conditions), then a flow computer determines the individual phase volume fractions at actual conditions using a PVT model and water-cut. This provides a measure of the oil rate at actual conditions. A shrinkage factor calculated by the black oil model is applied to report oil rate at standard conditions. Gas and water are also inferred in a similar manner. The gas, oil and water flow rates thus determined at actual conditions are further processed and converted to standard conditions as well.
The field tests showed that the SONAR Flow Surveillance approach allowed more flexibility in terms of field installation and the measurements are made at actual production conditions unlike other devices that may introduce additional flow restrictions. The SONAR meters diagnostics also provided a more realistic representation of the well flow profile since the measurements are instantaneous versus the "averaging" effects observed when using gravity-based separators. This allows better production surveillance and understanding of changes in well behavior.